The way backpressure works it helps give low end power. If you took away back pressure it gives you more upper rpm power but less low end torque. Reason why a full open exhaust on our cars isn't a good idea.

 

No actually you as usual do not.

 

Misinformation on backpressure abounds, even from an exhaust designer! Backpressure is not a good thing, period - look it up. It just happens that backpressure does increase when a restriction is added to the system which increases exhaust velocity. THAT'S what you want, higher exhaust velocity, NOT backpressure. The perfect system would have the highest velocity and the lowest backpressure - easier said than done.

 

I dont see how you can mandrel bend titanium anyway without very expensive machines. Those look like titanium welds (shiny). That exhaust will be loud due to the nature of Ti exhausts (thin walled) and the fact that there is two small resonators on it and a small muffler. That setup however will make good power, probably good for 15-20whp with straight pipes (and LOUD). With a turbo setup, that exhaust would sound great and make nice power. Ill warn you though, with a setup like that the exhaust will pop alot on downshifts.

 

Seriously +1

Chris

 

are you kidding?

 

I'd love to see an exhuast net 20whp!!!

 

and what do you know? from this post it's obvious you haven't done much research. I think ISMSolutions was generalizing the use of backpressure which probably led to your confusion.

exhuasts need the exhuast pulses to be reflected back at the exhuast valve at the correct time to keep the intake charge from being sucked out the exhuast during scavenging. so no 'back pressure' can equal loss of power when everything is not timed correctly.

it's all about the pulses of exhuast gases in the piping.

he probably used 'back pressure' as a simplified way to explain the exhuast gas pulses.

 

jdm my A$$.

Probably cdm (Chinese)

 

Saying backpressure is somehow needed just perpetuates the shade tree mechanics myth that backpressure is a good thing, when it's not.

If anyone is curious about all of this and would like to read a decent article explaining it, take a look at this one from Sport Compact Car
http://www.sportcompactcarweb.com/te...ems/index.html

Chris

PS lol, CDM

 

:-D You missed the straight pipes part. Most i'd see an exhaust gain is 10hp, tops.

 

Ever wonder why our cars loose low end power when we have a full open exhaust? Because no backpressure. We need some.

 

If you loose 5 torque down low but gain 5 torque up high which is the exhaust still worth it? Yeah- it is. 5 torque at a higher RPM has more influence on the final power of the car than 5 torque down low. Also, at higher rpms, the torque can be taken advantage of by more aggressive gearing.

 

Please enlighten me why you need an X or H pipe?

 

Gonna love his one...nice and ripe! So lets take my post IN CONTEXT - or should I say properly.

SO...I don't need to read up on backpressure, but I would suggest YOU DO! Backpressure is not a good things, that is partially correct. Too much backpressure, yes, but some is needed for proper scavenging. If you have a high compression car, a Turbo setup or SC...backpressure is the last thing you want ; HOWEVER, a turbo does introduce a restriction, that will result in backpressure, at some degree - pretty much right at the degree of need.

umm...not necessarily. Please don't make statements like that. It looks like your stating fact, of which it is not. You trying to say that all restrictions add velocity as there is an increase backpressure...not always the case. Adding a muffler or resonator, that may actually introduce a restriction, may also allow the gases to flow better, and actually reduce backpressure as a result.

Easier said than done...well only if you haven't researched, tested and built or designed vehicle specific exhaust systems before and you don't know your exhaust theory. BUT you suddenly did agree with me, as you wrote above ' the perfect system would have the highest velocity and the lowest backpressure". Now your stepping away from your statement in the beginning of your post. Did you just do some research and realized that your weren't totally correct?

So, if your talking about flow velocities, the idea is to keep the exhaust gases moving in the exhaust pipe, those gases will cause a small reduced-pressure area behind the closed exhaust valve, in the exhaust tube. These gases have momentum as they move away from the exhaust valve, creating a reduction in pressure, at the valve. When the exhaust valve opens, this reduced-pressure zone will help evacuate/scavenge the burnt gases from the cylinder. THIS IS THE DESIRED EFFECT!

When you have ZERO backpressure the exhaust gasses cool too quickly and loose their momentum, which is exactly why you need some backpressure. To get this done right, you not only have to make sure the pipe diameter is correct for the application, but also make sure the mufflers/resonators and pipe bends or headers, HFC's or testpipes, are all tuned correctly to get that DESIRED EFFECT.

So, I'm not talking about pulses here, yet...but maybe it's about time, as those gasses don't come out of the engine in one continuous stream. The exhaust valves open and close, exhaust gas will flow, then stop, and then flow again, as the exhaust valve opens - hence the pulse. The more cylinders you have, the tighter packed/closer together the pulses will be. If the pulses are not aligned properly, backpressure can be created, as well as rasp, etc.

So - the lower pressure end (the last pulse) of a series of exhaust pulses will attract the high-pressure portion (the front of the line) of the following pulse, effectively sucking/pulling it along - this creates a vacuum effect - EXTREMELY DESIRED. A tuned system allows the exhaust pulses to line up and pull each other along - in an effective and efficient manner.

The stock exhaust is so good at restricting - it'll actually ram the exhaust pulses together and make good low-end torque, and sacrifice top end HP. To get a better balance, and increase the top end power, you must design the exhaust system so that the pulses can more efficiently flow through the pipe, while maintaining good scavenging effect. To line up pulses properly, takes restriction - otherwise known as backpressure to many.

Headers are great additions to exhaust systems, when they are made properly for application. You will hear how people have put on headers and lost power, some who have gained, some who made better bottom end, and some who made better top end, and some who made nothing at all and figured they wasted their money. Headers, that we all have available to us, are designed to specifically work with the stock exhaust system. They promote scavenging, which in turn increases velocity and allows the pulses to line up better, as opposed to being packed together.

So for headers - if you match them to a system that has very little backpressure, and that is already tuned - you can completely mess the whole system up - by reducing backpressure even more - and completely defeating the entire purpose of installing them in the first place.

So again I will say - our cars need some backpressure - otherwise the pulses will not line up properly, the gases will cool too quickly, scavenging will not take place, and making power will not happen either. As I wrote above - too much backpressure = not good, but just the right amount is purely beneficial. ZERO backpressure should only be sought for high compression, force inducted or nitrous cars, where the exhaust pressure has been increased, in direct proportion to the intake pressures, whereby the velocity is high enough to not require scavenging, to keep the gases as hot as possible, once they travel to the end of the pipe.

If you restrict a system like that too much, you will not make power, however if the system does not make enough exhaust pressure to allow a truly free-flowing exhaust to be implored, then guess what - you need some restriction, or again as most refer to it, BACKPRESSURE.

Well... I hope you understand the context of my post now!

Oh yea - time for recess...school is out!

Rick

 

Great article - just read it after I posted...nothing contradictory for me...

 

This is an easy one!

X's and H's help to balance a dual exhaust system; align pulses, and completely promote highly efficient exhaust gas scavenging by increasing the vacuum effect of the low-end pulse. As the system is balanced, both banks of the engine can expel the exhaust gases evenly - which in turn produces more power. Most dual systems that do not have an X or and H pipe section, will see anywhere from 4-6HP on average, over the same system that does not have either in effect. The X-pipe is the most efficient for 4/6 cylinders, and it is gaining more respect, over the last 4-6 years for the V8 as well.

Rick

 

no

no

no

I am not exactly sure how you can write all that, then read the article and say its not contradictory.

What you are saying is that you need backpressure to get the best performance.

The article is saying the aim is for none but a some backpressure is unavoidable.

Its not the same.

Chris

 

Hmm.. I didnt expect many ppl would leave comments but it looks like you guys are interested in this exhust ~~ i will see if i can try and test it then i will post up some clips for you guys .. no promise though~~~
btw should i keep the hks or go for this full ti dual??

 

uhm..did you not see what other people said?

Many suggest to stick with your HKS. The exhaust your friend is offering you doesnt seem to have the best design (as explained by IMSOLUTIONS post.) But if youve got the cash, buy it and try it out before you sell your HKS.